This research deals with the hormonal control mechanisms involved with pituitary gland pituitary tumor function. Catecholamines are known to be important in inhibiting prolactin release by the pituitary gland but apparently have little effect on prolactin production in a prolactin-secreting pituitary tumor. Conversely ergotamine inhibits prolactin production by pituitary tumor but not the pituttary gland. The tissue receptor sites for these agents are sought. Growth hormone is not affected. The latter hormone is stimulated by 3'5' AMP, but the nucleotide has no effect on prolactin release. Pituitary tumors inhibit pituitary gland function in vivo, and investigations are directed toward the in vitro cell-free synthesis of the pituitary gland hormones using polyribosomes and cytosol fractions of the cell to determine the point of hormone feedback. Ribosomal and messenger RNA synthesis are being compared in the tissues.